I recently had an 11x14 mirror with a 2.5" wide pine frame that got
damaged while on display in a store. They had it hanging on a door
and it got knocked off, I'm guessing about a 4 foot drop. The weird
thing is the glass didn't break, except a small chip in one corner.
All 4 joints on the frame came apart though, which is sort of the
opposite of what I would have expected. They were splined miters with
the spline about 1 inch deep at the joint. It appears the splines
were either slightly too thin or I didn't use enough glue, as the
splines came loose with no damage at all to the frame or splines. I
test fitted one and it seemed like a proper fit to me. I'm a little
confused.

So here are my questions,

With the proper joinery should a frame survive a fall like this or
should it be expected to fail?

Should I be making the spline deeper or adding a key for additional
strength?


-Leuf